This invention relates to protecting integrated circuits and, more particularly, to protecting a power integrated circuit device from possible damage arising from the occurrence of voltage surges in a load connected to the device.
Power integrated circuit (PIC) devices (also referred to as smart-power devices) are utilized in a wide variety of industrial applications. In one such application, a PIC device is employed as a so-called high-side switch to connect a power supply to an associated load. In many cases of practical importance, the nature of the load is such that a disruption in the power supply or other similar malfunction will cause a relatively large voltage surge to appear across the load. The magnitude of this surge is often sufficient to irreversibly damage the PIC device and render it unsuitable for thereafter performing its intended function.
Accordingly, continuing efforts have been directed by workers skilled in the art aimed at trying to devise a simple and reliable arrangement for protecting a PIC device against load voltage surges. Prior art power integrated circuits with various protection schemes are shown in U.S. Pat. Nos. 4,489,341 and 4,521,795, European Patent Application EP 0 271 942 A2, and German Offenlegungsshrift DE 37 20 256A1. It was recognized that these efforts, if successful, would make these devices more attractive for utilization in important commercial applications where dependable long-lived operation is required.